Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 042311
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
611 PM CDT SAT JUL 4 2015

.SHORT TERM...(TONIGHT)
ISSUED AT 252 PM CDT SAT JUL 4 2015

A NICE 4TH OF JULY NIGHT LIES AHEAD FOR CENTRAL/SE IL FOR FIREWORK
DISPLAYS AT DUSK AS WEAK HIGH PRESSURE 1017 MB OVER CENTRAL IL
DRIFTS SLOWLY INTO THE OHIO RIVER VALLEY ON SUNDAY MORNING.
SCATTERED DIURNAL DRIVEN CUMULUS CLOUDS OF 4-5K FT WILL DISSIPATE AT
SUNSET LEAVING JUST SOME THIN CIRRUS CLOUDS ALONG WITH SOME HAZY
SMOKE FROM CANADIAN WILDFIRES ORIGINATING OVER THE NORTHERN HALF OF
ALBERTA AND SASKATCHEWAN. WITH FAIR SKIES...LIGHT TO CALM
WINDS...AND TEMPERATURES SETTLING TOWARD DEWPOINTS OF 60-65F
OVERNIGHT...PATCHY FOG SHOULD ONCE AGAIN DEVELOP AFTER MIDNIGHT
ESPECIALLY SE OF THE IL RIVER. COULD EVEN SEE PATCHY DENSE FOG
APPEAR IN A FEW SPOTS THOUGH HRRR NOT AS AGGRESSIVE WITH FOG
FORMATION AS IT WAS LAST NIGHT. ANY SHALLOW FOG THAT DOES DEVELOP
SHOULD LIFT QUICKLY BY MID MORNING SUNDAY.

.LONG TERM...(SUNDAY THROUGH SATURDAY)
ISSUED AT 252 PM CDT SAT JUL 4 2015

MAIN CONCERN REMAINS WITH THE TRACK OF THE INCOMING FRONTAL BOUNDARY
EARLY THIS WEEK. LATEST NAM MODEL HAS SLOWED DOWN QUITE A BIT AND
HAS IT JUST ENTERING THE FORECAST AREA AT SUNRISE TUESDAY...WHILE
THE REMAINING MODELS CONTINUE WITH THEIR EARLIER TRENDS OF BEING
JUST EAST OF I-55 BY THAT TIME. A BLEND OF THE GFS AND ECMWF WAS
USED FOR THE EARLY WEEK WEATHER.

HAVE LIMITED MENTIONABLE POP`S MONDAY AFTERNOON TO AREAS ALONG AND
WEST OF THE ILLINOIS RIVER...WITH THE MAIN SHOW COMING MONDAY NIGHT
AND TUESDAY. GFS CONTINUES TO ADVERTISE COPIOUS MOISTURE WITH THIS
SYSTEM...WITH PRECIPITABLE WATER VALUES IN THE 2-2.25 INCH RANGE.
SUCH VALUES LINGER ACROSS AREAS ALONG/SOUTH OF I-70 INTO
WEDNESDAY... ALTHOUGH IT IS ALSO A BIT FURTHER NORTH THAN THE ECMWF
ON STALLING THE FRONT IN SOUTHERN ILLINOIS. WILL NEED TO WATCH THE
HEAVY RAIN POTENTIAL IF THIS INDEED STALLS OVER OUR AREA...BUT IN
THE MEANTIME WILL CONTINUE THE LIKELY POP`S SOUTH OF I-70 THROUGH
WEDNESDAY. ANY SEVERE WEATHER WOULD MOST LIKELY BE MONDAY
NIGHT...BUT POTENTIAL REMAINS LOW (5% ON LATEST SPC DAY3 OUTLOOK) AS
THE FRONT WOULD BE ARRIVING AT AN UNFAVORABLE TIME.

LONGER RANGE MODELS ARE TRENDING MORE TOWARD A NORTHWARD SURGE IN
THE FRONT...IN RESPONSE TO A SHORTWAVE TRYING TO EJECT NORTHEAST
FROM THE SOUTHERN PLAINS. HOWEVER...THE UPPER PATTERNS ARE SHOWING A
FAIR RANGE IN THESE MODELS...WITH THE ECMWF HAVING MORE OF A SPLIT
FLOW CONVERGING JUST TO OUR SOUTH AND THE GFS WITH IT MORE OVERHEAD
OR JUST TO OUR NORTH. THIS WILL AFFECT WHERE EXACTLY TO FOCUS THE
HIGHER POP`S LATE IN THE WEEK...BUT HAVE LIMITED THEM TO AROUND 40%
UNTIL MORE AGREEMENT COMES INTO PLAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 611 PM CDT SAT JUL 4 2015

A LARGE AREA OF HIGH PRESSURE WILL CONTROL THE WEATHER ACROSS THE
REGION OVERNIGHT BRINGING LIGHT/VARIABLE WINDS. THE HIGH WILLSHIFT
EAST BY DAYBREAK SUNDAY ALLOWING LIGHT SE/S WINDS TO DEVELOP AND
STRENGTHEN TO 5-9 KTS BY LATE MORNING. ASIDE FROM SCATTERED CIRRUS
TONIGHT AND SCATTERED DIURNAL CU SUNDAY LATE
MORNING/AFTERNOON...SKIES WILL BE MOSTLY CLEAR. DUE TO THE
LIGHT/CALM WINDS AND RADIATIONAL COOLING OVERNIGHT...FOG IS
EXPECTED WITH WIDESPREAD MVFR VISIBILITY AFTER 06-08Z AND THROUGH
AROUND 15Z. SOME VSBYS MAY DROP AS LOW AS 2SM AT
TIMES...ESPECIALLY AT KDEC AND KSPI...FROM 08-12Z.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...07
LONG TERM...GEELHART
AVIATION...25



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